This invention relates generally to the assembly of trusses, and in particular to a gantry press for assembling trusses which provides several advantageous features.
Pre-manufactured structural frameworks, such as trusses, are widely used in the construction industry for forming a roof, wall panel, floor, or other building component. Each truss includes a collection of wooden, plastic, or metallic truss members held together by connectors, such as nailing plates. The truss is assembled to the correct specifications at a factory and then shipped to a construction site. A gantry press apparatus is frequently used to facilitate efficient assembly of the truss. It features a table on which the truss members and connectors are placed at desired relative positions to form the particular truss configuration. A motorized roller apparatus (i.e., the gantry) then travels along the table to press the connectors into the truss members thereby joining them together. The roller apparatus includes a cylindric roller, two opposite supports, and several wheels mounted on wheel guides along opposite sides of the table. After traversing the length of the table, the roller apparatus continues moving along the guides and is stopped in a parking area at an end of the table such that the assembled truss can be freely removed from the table without obstruction by the roller apparatus.
The present invention improves upon gantry press devices of the prior art, which unfortunately have a number of potential difficulties. For example, initial installation of the table to a perfectly level orientation can be time consuming. Legs of the table have a fixed height, with a height-adjusting bolt attached to each leg and positioned at or near the ground. A relatively narrow width of the bolt leaves the table subject to rocking, and its position makes it difficult to adjust.
Prior art supports of the roller apparatus are subject to becoming warped or misaligned relative to the table. Typically these supports comprise frames assembled from several pieces which are welded together, and consequently are subject to inaccuracies in attachment or tolerance stack-up. Further, the frames have a relatively lighter weight which permits deflections (warp) under typical loads.
Operators control the roller apparatus with a joystick controller for varying speed. There is no automated slow-down when the roller apparatus reaches the parking area, and consequently operators can inadvertently permit the roller apparatus to continue moving through the parking area into collision with an end stop. That collision typically causes damage.
Wheel guides become worn due to repetitive use and contact from wheels, and replacement of guides on prior art systems is expensive and time consuming. Guides typically comprise bars, tubes, or tracks securely mounted along opposite sides of the truss table for supporting and directing movement of the roller assembly relative to the truss table. When worn, replacement of the guides is costly and results in substantial down time for the apparatus.
The roller is constructed with a central shaft and axial disks mounted on the shaft to support a cylindric outer surface of the roller. Strength and durability of the roller are degraded when the axial disks are attached to the shaft by direct welding. Welding crystallizes certain materials at the weld, leading to subsequent cracks or breakage.
Reference is made to the following co-assigned U.S. patents for further background regarding truss assembly systems, which are hereby incorporated by reference:
Among the several objects and features of the present invention may be noted the provision of a truss assembly apparatus having a truss table which may be readily adjusted to a level orientation and adjusted in height; the provision of such an apparatus which provides accurate alignment between a roller apparatus and a table; the provision of such an apparatus which has a strong and durable roller; the provision of such an apparatus which inhibits collision into an end stop; and the provision of such an apparatus which provides for rapid and cost effective repair when wheel guides become worn.
In general, a gantry press apparatus of the present invention is for assembling a truss. The truss has at least two truss members and at least one connector for connecting the truss members. The apparatus comprises a truss table including a worksurface on which the truss members may be positioned. A roller assembly is movable relative to the truss table and configured to press at least one connector into the truss members to join the truss members. At least one guide is for guiding movement of the roller assembly relative to the truss table, the guide extending generally along a side of the table. A wear strip is mounted on the guide and defines a surface engageable by the roller assembly as the roller assembly moves. The wear strip is removably secured to the guide so that the wear strip may be replaced with a different wear strip without replacement of the guide.
In another aspect, a gantry press apparatus of the present invention is for assembling a truss. The truss has at least two truss members and at least one connector for connecting the truss members. The apparatus comprises a truss table including a worksurface on which the truss members may be positioned. A roller assembly is movable relative to the truss table and configured to press at least one connector into the truss members to join the truss members. A plurality of legs are for supporting the table at a position spaced above an underlying floor. At least some of the legs are telescopically adjustable in height, each having an upper leg member telescopically moveable relative to a lower leg member such that the legs may be selectively manipulated to place the table at a level orientation.
In yet another aspect, a gantry press apparatus of the present invention is for assembling a truss. The truss has at least two truss members and at least one connector for connecting the truss members. The apparatus comprises a truss table including a worksurface on which the truss members may be positioned. A roller assembly is movable relative to the truss table and configured to press at least one connector into the truss members to join the truss members. The roller assembly comprises spaced apart supports, a cylindric roller rotatably coupled to and extending between the supports, and at least one horizontal spacer extending between and interconnecting the supports. Each support is formed of a one piece plate configured to inhibit deflection of the plate under loads experienced by the plate.
In still a further aspect, a gantry press apparatus of the present invention is for assembling a truss. The truss has at least two truss members and at least one connector for connecting the truss members. The apparatus comprises a truss table including a worksurface on which the truss members may be positioned. A roller assembly is movable relative to the truss table and configured to press at least one connector into the truss members to join the truss members. At least one guide is for guiding movement of the roller assembly relative to the truss table, the guide having an end region generally beyond the worksurface. A motor system is for driving the roller assembly along the guide. A mechanism is for controlling the motor system to automatically reduce a speed of the roller assembly when the roller assembly moves beyond a predetermined position within the end region of the guide.
In one more aspect, a roller of the present invention is for use in a gantry press apparatus for assembling a truss having at least two truss members and at least one connector for connecting the truss members. The roller comprises a central shaft which is rotatably mounted in the apparatus, the shaft having a longitudinal axis and a diameter. A cylindrical drum is rotatable with the shaft and has an outer surface configured for pressing at least one connector into the truss members to join the truss members. At least two support disks are positioned inside the drum, each disk being coaxially aligned with the shaft and having opposite faces and an outer circumferential surface in engagement with an inner surface of the drum. An annular sleeve is mounted on the shaft, the sleeve including an inner surface having an inner diameter, an outer surface, and an axial end attached to one of the disks. The inner diameter of the sleeve is less than the diameter of the shaft such that the sleeve is mounted on the shaft with an interference fit free of a welded connection.
Other objects and features of the present invention will be in part apparent and in part pointed out hereinafter.